Baseball and softball bats, hereinafter referred to simply as “bats”, are today typically made solely from aluminum alloys, or aluminum alloys in combination with composite materials (hybrid bats), or most recently solely from composite materials (with the exception of solid wooden bats for the Major Leagues). Such bats are tubular (hollow inside) in construction in order to meet the weight requirements of the end user, and have a cylindrical handle portion for gripping, a cylindrical barrel portion for striking, and a tapered mid-section connecting the handle and barrel portions.
When aluminum alloys initially replaced wooden bats in most bat categories, the original aluminum bats were formed as a single member, that is, they were made in a unitary manner as a single-walled aluminum tube for the handle, taper, and barrel portions. Such bats are often called single-wall aluminum bats and were known to improve performance relative to wooden bats as defined by increased hit distance. Such bats have constant stiffness along their barrel portion length.
All such prior art single wall bats, of any material, have cylindrical handle portions with diameters less than 1″, cylindrical barrel portions with diameters greater than 2″, both portions continuous with a cylindrical taper portion increasing in diameter from the handle portion to the barrel portion.
U.S. Pat. No. 5,303,917 to Uke discloses a tubular bat with a handle portion and a barrel portion shaped at their innermost ends to telescope and overlap together along a single area of contact. Both portions are not of uniform cross-section, do not extend the full length of the bat, and are not isolated from each other.
More recently (in the mid 1990's), improvements in bat design largely concentrated on further improving bat performance. This was accomplished primarily by thinning the barrel or hitting portion of the bat frame and adding inner or internal, and/or outer or external, secondary members extending along the entire barrel length. These members are often referred to respectively as inserts or sleeves; while the main member is often referred to as a body, shell or frame in the prior art. Such bats are often called double-wall bats or multi-walled bats in the case of more than two walls.
The prior art of such double walled and multi-walled tubular bats generally refers to improved performance or hit distance resulting from trampoline effect, spring, compliance, rebound, flexibility, etc. resulting from the multi-wall two or more member construction along the entire barrel length allowing the barrel portion of the bat to deflect or flex more upon ball impact which propels the ball faster and further than prior art bats.
All such prior art tubular bats have a sweetspot, generally two or four inches in length, located centrally along the barrel portion length. The sweetspot is the barrel portion length of maximum bat performance as defined by batted ball distance. As the batted ball location moves away from the sweetspot area towards either the barrel extreme end or the taper end, bat performance progressively decreases.
U.S. Pat. No. 5,364,095 to Easton discloses a double-wall bat consisting of an external metal tube and an internal composite sleeve bonded to the inside of the external metal tube and running full length of the barrel portion of the bat. Further, U.S. Pat. No. 6,042,493 to Chauvin, et al. discloses a double-wall bat with an insert made of titanium and composite materials.
U.S. Pat. No. 5,415,398 to Eggiman discloses a double-wall metallic bat consisting of a frame and internal insert of constant thickness running full length of the barrel portion of the bat in a double-wall construction. Further, U.S. Pat. Nos. 6,251,034B1 and 6,482,114B1 disclose variations to U.S. Pat. No. 5,415,398. Further, U.S. Pat. No. 6,251,034B1 discloses a polymer composite second tubular member running full length of the barrel portion of the bat with the barrel members joined at the ends only of the barrel portion with the balance of the composite member freely movable relative to the primary member. U.S. Pat. Nos. 6,440,017B1 and 6,612,945 B1 to Anderson also disclose double-wall bats with an outer sleeve and inner shell of constant thickness running full length of the barrel portion.
U.S. Pat. No. 6,053,828 to Pitsenberger discloses a double-wall bat consisting on an internal body and an external shell of constant thickness running full length of the barrel portion in a double-wall construction. U.S. Pat. No. 6,461,260B1 to Higginbotham discloses the bat of U.S. Pat. No. 6,053,828 with a composite shell formed to an outer shell running full length of the barrel portion of the bat.
Similarly, U.S. Pat. No. 6,425,836B1 to Misono discloses a double-wall bat with a lubricated coating between layers or a weak boundary layer formed on the surfaces of the inner member.
U.S. Patent Pub. 2001/0094892 A1 by Chauvin discloses a double-wall bat consisting of an outer shell and an insert laminate partially bonded to the shell.
In all prior art multi-walled tubular bats, the primary bat frame member and secondary barrel member(s) extend along the entire barrel length and are of constant thickness. Also, the bat members in the barrel portion are not joined, except at their ends, in order to reduce radial stiffness of the barrel portion to improve bat performance. This provides a trampoline effect which is greatest in the central barrel area called the sweetspot. Increasing the barrel portion, or hitting area, increases the sweetspot size similarly to increasing the hitting areas of tennis racquets and golfclubs.
All such prior art double wall bats, of any material, have cylindrical handle portions and cylindrical barrel portions. Both portions being continuous with a cylindrical taper portion increasing in diameter from the handle portion to the barrel portion. It is well known that hits in the sweetspot area do not produce unpleasant sting in the batter's hands while hits away from the sweetspot area, particularly close to either extreme barrel portion ends, results in unpleasant sting in the batter's hands.
The sting in the batter's hand is due to rapid vibration movement of the handle portion generated by the violent and high free impact of the ball and the bat barrel portion away from the sweetspot area. The vibration energy of the ball impact travels from the barrel, through the taper, to the joined handle portion of prior art bats. In an attempt to reduce sting, cushioned grips, and padded gloves, special endcaps, foam interiors and other such means are well known at best to provide minimum relief.
U.S. Pat. No. 5,593,158 to Filice discloses a tubular bat with a handle portion and a barrel portion shaped to overlap along a single area of contact in the taper region and separated by thin elastomeric material to attenuate vibrations. Both bat portions are not of uniform cross-section and do not extend full length of the bat. Such bats only provide minimal relief from sting due to such elastomeric material being highly rate, or time, dependant; that is, the extremely rapid vibrational bat movements, are minimally attenuated.
In summary, prior art bats have hitting area sizes (i.e. barrel portion lengths) limited by materials employed, traditional bat geometries and desired finished weights. Further, prior art bats have limited length sweetspot areas of highest bat performance and traditional geometries such that off sweetspot hits cause vibrations resulting in unfavourable sting in hitter's hands. All such prior art bats have traditional circular tubular handles that are considerably shorter than the full bat length and/or have a non-uniform cross-sectional area along the taper portion length; and whose barrel and handle portions are in contact at one distinct locational area only; and thus whose barrel and handle portion perform dependently with each other.
Therefore, what is needed are tubular bats with larger hitting areas in order to allow batters to increase the percentage of hitting area ball contacts to in turn increase batting average, a fundamental measure of player performance. It is also well known that by increasing the hitting area, the sweetspot increases in size and the trampoline effect increases, thereby improving performance as defined by hit distance. Further, what is needed are tubular bats with larger sweetspot areas, ideally full length of the hitting area barrel portion, which increases the area of maximum bat performance. Also, larger sweetspot areas decrease the number of off sweetspot ball contacts which cause unfavourable sting in the batters hands. Further, what is needed is tubular bats which minimize sting, and ideally eliminate sting, due to off sweetspot ball contacts.